Preparation and Characterization of FeCo2O4 Nanoparticles: A Robust and Reusable Nanocatalyst for the Synthesis of 3,4-Dihydropyrimidin- 2(1H)-thiones and Thiazolopyrimidines

Background: The present research describes a mild and efficient method for the synthesis of 3,4-dihydropyrimidine-2(1H)-thiones and thiazolopyrimidine via multi-component reactions using FeCo2O4 nanoparticles. It was found that FeCo2O4 nanoparticles act as a powerful and effective catalyst. The prepared catalyst was characterized by the various spectroscopic techniques. Objective: The three-component reaction of thiourea, aromatic aldehydes and ethyl acetoacetate was catalyzed by FeCo2O4 nanoparticles. Next, the prepared 3,4-dihydropyrimidin-2(1H)-thiones were applied for the preparation of thiazolopyrimidines via the reactions of 3,4-dihydropyrimidine-2(1H)- thiones, chloroacetic acid, and aromatic aldehydes in the presence of FeCo2O4 nanoparticles. Methods: The FeCo2O4 nanoparticles were synthesized by a facile one-step method and the structure determination of the catalyst has been done using spectral techniques. Then, the prepared nanocatalyst was used in the synthesis of 3,4-dihydropyrimidin-2(1H)-thiones and thiazolopyrimidines under solvent-free conditions at 80°C. Results: FeCo2O4 nanoparticles as a magnetic nanocatalyst were applied as a catalyst in the synthesis of some heterocyclic compounds in excellent yields and short reaction times. The average particle size of the catalyst is found to be 30-40 nm. The study on the reusability of the FeCo2O4 nanoparticles showed the recovered catalyst could be reused fifth consecutive times. We propose that FeCo2O4 nanoparticles act as a Lewis acid cause to increase electrophilicity of carbonyl groups of substrates and intermediates to promote the reactions. 2 Conclusion: The present research introduced various advantageous including excellent yields, short reaction times, simple workup procedure and recyclability of the FeCo2O4 NPs in order to the synthesis of 3,4-dihydropyrimidin-2(1H)-thiones and thiazolopyrimidines.